Istanbul's chief prosecutor has filed warrants for the arrest of a top aide to Saudi Arabia's de facto ruler and the deputy head of its foreign intelligence on suspicion of planning the killing of Jamal Khashoggi, according to Turkish officials.

"The prosecution's move to issue arrest warrants for Asiri and Qahtani reflects the view that the Saudi authorities won't take formal action against those individuals," one of the Turkish officials said.

"The international community seems to doubt Saudi Arabia's commitment to prosecute this heinous crime.

"By extraditing all suspects to Turkey, where Jamal Khashoggi was killed and dismembered, the Saudi authorities could address those concerns," the official said.

"You have to be wilfully blind not to come to the conclusion that this was orchestrated and organised by people under the command of MbS," Republican Senator Lindsey Graham told reporters after the meeting with CIA director Gina Haspel, referring to the Crown Prince by his initials.

Mr Graham, who has become one of the President's most vocal allies, said there may not be a "smoking gun", but that there was a "smoking saw", a reference to a bone saw that investigators said was used to cut up Mr Khashoggi's body.